Showing papers on "Solar power published in 1993"

Controlled power interface between solar cells and AC source

Abstract: A novel interface circuit between solar cells and a commercial AC source using Van Allen's multivibrator is presented. In this circuit, the AC source is used as a backup for solar cells, and the source and load power flow is automatically balanced by the circuit itself without any external phase control. Based on the analysis of the characteristics of solar cells and Van Allen's multivibrator, the authors describe a new method of controlling the DC power from solar cells according to the current load conditions, and a simple and fast optimization method for deriving the maximum solar power is discussed. >

Sun-referenced safe-hold control for momentum biased satellites

Abstract: A sun-referenced safe-hold control system for momentum-biased satellites employs a safe-hold processor responsive to a set of sun sensors to detect attitude errors of the solar wings. Safe-hold processor provides independent control logic which rotates the solar wings to ensure that sunlight is maintained incident on the solar wings to maintain solar power in the safe-hold mode. In addition, the safe-hold processor provides independent control of the momentum wheel to place the spacecraft body in a passively stable nutational state. Passive nutational stability inherent in a momentum-biased satellite about two axes of the spacecraft enables the safe-hold processor to actively control the spacecraft about only one of its axes. The spacecraft safe-hold control system increases the period in which spacecraft health is guaranteed by adding active, closed-loop control of the solar wings.

Automatic vehicular ventilating system

Abstract: An automatic vehicular ventilating system ventilates the passenger room of a vehicle such as automobiles, aircraft, railway passenger cars and ships to maintain air in the passenger room at a fixed temperature automatically. The automatic vehicular ventilating system includes a solar power supply unit having a solar panel as a power supply, a first switch responsive to the output of a thermostat, and a second switch in communication with at least at least one of an ignition switch of the vehicle and a hand brake of the vehicle; an exhaust unit having an air exhaust damper; and a fresh air supply unit having an air supply damper. The air exhaust damper and the air supply damper are driven by electric power supplied from the solar power supply unit.

Satellite solar power station

Abstract: The finiteness of the Earth's fossil-fuel reserves are discussed and the world energy needs are projected to show that alternative energy sources to nuclear power merit consideration. A satellite solar power station is proposed to generate power to meet future requirements. Considerations are given to orbital location, solar energy conversion devices, transmittal equipment and Earth-receiving stations. The use of photoconductive organic materials to form thin film solar collector surfaces and generation of microwave radiation to transmit energy to an Earth-based antenna are discussed. The design considerations and the development tasks for a large satellite solar power station are reviewed and the potential technological needs are identified. The suggestion is made that the technology developed for the space program may find application in a satellite solar power station to generate power for use on Earth.

Fuzzy logic controller for maximum power tracking in line-commutated photovoltaic inverter scheme

Abstract: The paper presents simulation and implementation of a photovoltaic fuzzy logic tracking controller. The purpose is to track the maximum available solar power in a photovoltaic array interfaced to an electric utility grid via a line-commutated inverter. The scheme shows a satisfactory performance with almost an agreement between the simulation and experimental results. >

Solar Heating with Seasonal Storage. Some Aspects of the Design and Evaluation of Systems with Water Storage

Abstract: The report provides a basis for detailed design and evaluation of future solar heating plants with an insulated seasonal water storage. The importance of careful design and plant commissioning is pointed out and a system simulation model for future analyses of system performance is provided. A general evaluation methodology is presented. A pilot plant is described and used as an evaluation example. A system simulation model is formed and validated for the actual system performance in the pilot plant. The simulation model is then used to generalise the results in a parametric study. Sensitivity analyses for modified designs are carried out. The influence on thermal performance of some system design parameters is related to the change in collector area that will give the same amount of net solar coverage for a given storage and load. The report includes important design aspects of storage system layout and collector system heat capacity rate, which confirms earlier recommendations by the author. The influence of storage design on thermal performance is also presented in a similar way for a given collector and load. The cost permissible for a modified design is presented in relation to marginal collector cost. This way of presenting the results enables cost analyses to be performed by those designers who have the necessary knowledge to make an improved design.

Parametric cost model for solar space power and DIPS systems

Abstract: A detailed cost model has been developed to parametrically determine the program development and production cost of photovoltaic, solar dynamic, and dynamic isotope (DIPS) space power systems. The model is applicable in the net electrical power range of 3 to 300 kWe for solar power and 0.5 to 10 kWe for DIPS. Application of the cost model allows spacecraft or space-based power system architecture and design trade studies or budgetary forecasting and cost benefit analyses. The cost model considers all major power subsystems (i.e., power generation, power conversion, energy storage, thermal management, and power management/distribution/control). It also considers system cost effects such as integration, testing, and management. The cost breakdown structure, model assumptions, ground rules, bases, cost estimation relationship format, and rationale are presented, and the application of the cost model to 100-kWe solar space power plants and to a 1.0-kWe DIPS is demonstrated. >

The rise and fall of Luz

Abstract: In the search for renewable power the United States has established tax credits for power plants that use solar or wind energy. These tax credits are, of course, eventually paid by the taxpayers and must be justified by the politicians. And there's the rub. When a solar plant becomes big, the taxpayers' contribution grows so large that politicians have a hard time justifying it. The experience of Luz describes how this company's success in building solar plants inevitably led to its demise. It brings into question whether we're serious in the pursuit of solar power or whether we merely pay lip service.

Concentrator arrangement for increasing efficiency when using solar power

Abstract: The invention describes novel techniques in the exploitation of solar power, which are specified by the following detials: a) The beams are deflected in the reflectors by an easily replaceable reflecting film. b) By using parabolic mirrors for concentrating virtually unlimited solar power on solar cells and/or solar collectors, their efficiency is considerably increased. c) By novel design and arrangement of the solar cells and solar collectors, which are each located at the focal points of the reflectors. d) Arrangement of a finite number of the reflectors on a mast with central solar tracking.

Solar power generating equipment

Abstract: PURPOSE:To make it possible to use solar energy to a maximum and to reduce fluctuation in electric power supplied to a load even when part or whole of a solar power generating equipment mounted on a solar car is located in shade. CONSTITUTION:Each block has a plurality of solar cell elements 1a ...1i connected in series and a capacitor C connected in parallel to the block. A plurality of the blocks B1 ...Bj are connected in series; a reverse current blocking diode D is connected in series to each row, and a plurality of rows L1, L2 ...Lm are connected in parallel. A load circuit 10 in which a control switch 11, a DC/DC inverter 12 and a DC motor 13 for driving a solar car are connected in series is connected between both the ends of said parallel circuit.

Control circuit of inverter for solar power generation

Abstract: PURPOSE:To realize compensation for reactive power and higher harmonics to prevent inverse power flow. CONSTITUTION:In a conventional circuit, a voltage regulator 12 for matching an output voltage of a solar battery with its command value and a multiplier 15 for obtaining a command value of an output current of an inverter from an output thereof and a sine wave AC component synchronized with the system are provided to realize control based on an output thereof. Therefore, it has been impossible to sufficiently supply reactive power and higher harmonic components. However, such reactive power and higher harmonic components can be compensated by detecting a load current IL and realize the control operation using a value obtained by adding such load current IL to an output of the multiplier 15 as a new current command value IINV*. Moreover, inverse power flow can also be prevented.

Renewable energy supplies for radio systems for servicing rural customers

Abstract: BT has used solar powered equipment for about 18 years, and there are three such known installations in the UK local access network (all powering single channel radio sets). However, these are all very low powered applications (average consumption less than 1 W), and can be satisfied from a modest sized solar panel float-charging a small battery. This paper describes a further example, from the BT telephone network, where a customer was supplied with a radio system with very much higher power consumption, and which was powered successfully by a renewable energy source. >

Solar power safety lamp for automobile

Abstract: The utility model discloses a solar power safety lamp for automobiles used for illumination of bicycles and automobiles. When a light source is existed, a solar energy plate (Solar) can receive light energy and convert the light energy into electrical energy. Thus, a battery can be charged through the control of an electric circuit board apparatus. When the light source is not existed, the solar energy plate (Solar) can stop absorbing the light energy. Thus, the rechargeable battery can automatically discharge the electrical energy through the control of the circuit board, and then a diode LED is in luminescent state. The solar power safety lamp comprises a shell, a transparent upper cover on the top pf the shell, a transparent panel at the front, and the solar energy plate and the circuit board which are arranged in shell.

Solar power generation system

Abstract: PURPOSE:To provide the solar power generation system which efficiently operates an inverter while performing the maximum power following-up control, which maximizes the generated power, in all of the period of power generating operation. CONSTITUTION:This system is provided with a solar battery 1, plural inverters 2A and 2B which convert the output of the solar battery 1 to an AC to connect it to a power system 4, a controller 5 which performs the maximum power following-up control of the specific inverter 2A, and a controller 6A which allots the generated power outputted from the solar battery to respective inverters and controls the outputs of inverters so that the efficiency of the whole of the system is maximum.

Advanced Space Photovoltaic Technology

Abstract: Solar arrays have been the predominate power sources in space for over thirty years, beginning with the launch of the first U.S. solar powered satellite in 1958 [Ref. 1] . Since that time, hundreds of kilowatts of solar power have been placed in orbit on commercial, civilian and military satellites, and small arrays have been transported and left behind on the surfaces of the Moon and Mars. At least one photovoltaic array has been in orbit for nearly two decades, and is still functional [Ref. 2]. Solar cell efficiencies on the earliest arrays were low, typically around 10%, and much had to be learned about the survivability of solar cells in the space environment. Enormous progress has been made since 1958, both in our understanding of the fundamental mechanisms which limit solar cell efficiency and lifetime, and in our ability to turn that understanding into real system improvements. In the pages that follow we will describe the technologies presently being pursued by the National Aeronautics and Space Administration to develop advanced solar cells and arrays, and discuss briefly the improved system capabilities which should result.

Domestic solar power supply

Abstract: The utility model discloses a domestic solar power supply which converts solar energy into 220V /50Hz alternating current power supply, comprising a solar panel, storage cells, a control circuit, a voltage indicating circuit, and an inversion boosted circuit. The utility model is characterized in that a control relay is connected with a switch in series and then connected with the storage cells and a trimmer potentiometer in parallel; the solar panel is connected with the storage cells in parallel through anti-inversion diodes; the two normally open contacts of the relay are respectively connected with the two input terminals of the inversion boosted circuit. According to the principle of photoelectric conversion, the storage cells are charged by the output voltage of the solar panel, and 220V /50Hz alternating current power supply is output through a voltage indication circuit and the inversion circuit. As a result, the electric need of residents' homes in areas with no power or short power supply or frequent power failure is solved.

Solar power generating facility

Abstract: PURPOSE:To improve efficiency, to reduce cost and to miniaturize the facility by reducing the capacity of a converter for controlling the generated power of a solar battery at a maximum. CONSTITUTION:A serial circuit composed of a solar battery 1 and an AC/DC converter 2 is parallelly connected to a capacitor 4 for smoothing a pulse voltage obtained from a power system 8 through a rectifier 3, and DC power is supplied from both of the terminals of the capacitor 4 to an inverter 5 for driving a load 6. In this case, the output voltage of the AC/DC converter 2 is controlled by being increased/decreased by a control part 7 so that the generated power of the solar battery 1 can be made maximum.

Solar Power and Climate Change Policy in Developing Countries

Abstract: Solar energy is one option for reducing future greenhouse gas emissions. Offsetting 50% of all future growth in thermal electricity generation by photovoltaics (PVs) would reduce annual global carbon dioxide emission from projected increased levels by 10% in 20 years and 32% in 50 years. Several projects are under way worldwide to demonstrate the feasibility of PV systems. This paper examines the economic competitiveness of PV systems and concludes that even after including externality costs, without significant technological breakthroughs, the economics of PV applications are unlikely to allow for an unsubsidized, widespread adoption of this technology in the near future. Further, if the goal of PV transfer programmes is to limit future greenhouse gas emissions, there are larger and cheaper opportunities available in industrialized countries to achieve reductions. Alternative measures for ensuring a market for photovoltaics, hence providing manufacturers with opportunities to improve the current technology, include mandating that utilities install a certain quantity of solar technologies by a certain date. Finally, moving towards a renewable energy future that includes PV systems requires a sustained R&D programme that will lead to improvements in panel and other system efficiencies.

Village power plants versus solar home systems

Abstract: Figures on rural energy consumption is presented along with past experience in rural electrification projects which show clearly the limits of any rural electrification policy. Three alternatives are compared using a network for electricity distribution, i.e. connection to the national grid, village networks with diesel and solar power stations, and the solar home system.